If the textures get lower by distance, than make sure you have on Anisotropic Filtering (unless you are using an enb, which would do that on its own.). Also, make sure you retry archive invalidation and make sure it is working properly. Other than that, I can't think of anything atm that could help besides that.

Firstly, make sure archive invalidation is on. Also you can install this road texture (in the optional files): http://www.nexusmods.com/newvegas/mods/42028/?tab=2&navtag=http%3A%2F%2Fwww.nexusmods.com%2Fnewvegas%2Fajax%2Fmodfiles%2F%3Fid%3D42028&pUp=1It looks great and seems to fix the issue with NMC roads.